feat(core): support pinned Code Mode tools (#39550)

packages/core/test/codemode.test.ts

@@ -16,6 +16,7 @@ describe("CodeMode", () => {
             description: "Echo text",
             input: Schema.Struct({ text: Schema.String }),
             output: Schema.String,
+            options: { pinned: true },
             execute: ({ text }) => Effect.succeed({ output: text }),
         }),
       )
@@ -27,6 +28,7 @@ describe("CodeMode", () => {
           path: "echo",
           description: "Echo text",
           signature: "tools.echo(input: {\n  text: string,\n}): Promise<string>",
+          pinned: true,
         },
       ])
     }).pipe(